Browsing by Author "Pekola, J."
Now showing 1 - 3 of 3
- Results Per Page
- Sort Options
- Entropy production in a non-Markovian environment
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2015-07-06) Kutvonen, A.; Ala-Nissila, T.; Pekola, J.Stochastic thermodynamics and the associated fluctuation relations provide the means to extend the fundamental laws of thermodynamics to small scales and systems out of equilibrium. The fluctuating thermodynamic variables are usually treated in the context of either isolated Hamiltonian evolution, or Markovian dynamics in open systems. However, there is no reason a priori why the Markovian approximation should be valid in driven systems under nonequilibrium conditions. In this work, we introduce an explicitly non-Markovian model of dynamics of an open system, where the correlations between the system and the environment drive a subset of the environment out of equilibrium. Such an environment gives rise to a new type of non-Markovian entropy production term. Such non-Markovian components must be taken into account in order to recover the fluctuation relations for entropy. As a concrete example, we explicitly derive such modified fluctuation relations for the case of an overheated single electron box. - Nanosecond Thermometry with Josephson Junctions
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2018-10-29) Zgirski, M.; Foltyn, M.; Savin, A.; Norowski, K.; Meschke, M.; Pekola, J.We demonstrate a new paradigm in nanoscale thermometry exploiting well-known switching measurements of a superconducting weak link. Such a weak link probed with nanosecond current pulses serves as a temperature-sensing element and, because of the fast inherent dynamics, is capable of delivering unprecedented temporal resolution. We use the thermometer to measure the dynamic temperature of electrons in a long superconducting wire relaxing to the bath temperature after application of a heating pulse, involving evaluation of the retrapping time. Our measurement delivers resolution better than 10 ns, with potential for further improvement. It extends the temporal resolution of existing experiments and introduces new possibilities for investigating thermodynamics at the nanoscale. - Nonequilibrium fluctuations in quantum heat engines: Theory, example, and possible solid state experiments
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2015-03-20) Campisi, M.; Pekola, J.; Fazio, R.We study stochastic energetic exchanges in quantum heat engines. Due to microreversibility, these obey a fluctuation relation, called the heat engine fluctuation relation, which implies the Carnot bound: no machine can have an efficiency greater than Carnot's efficiency. The stochastic thermodynamics of a quantum heat engine (including the joint statistics of heat and work and the statistics of efficiency) are illustrated by means of an optimal two-qubit heat engine, where each qubit is coupled to a thermal bath and a two-qubit gate determines energy exchanges between the two qubits. We discuss possible solid-state implementations with Cooper-pair boxes and flux qubits, quantum gate operations, and fast calorimetric on-chip measurements of single stochastic events.